Australia’s northern cattle herd produces one third less methane than previously believed, according to CSIRO research.

The results of a five year study, revealed at a field day near Townsville last Friday, indicate that cattle have been burdened with more than their fair share of blame for global warming under existing greenhouse gas calculation methods.

The CSIRO used custom-built respiration chambers and laser measurement systems to measure actual emissions from Brahman cattle fed on a wide range of tropical grasses over the past five years.

CSIRO research leader Dr Ed Charmley said the results indicated that methane emissions were up to 30 percent lower than the amount currently attributed to the northern beef herd in Australia’s greenhouse gas accounts.

“While you always have to be cautious in extending lab data to the field and across an industry, we have been able to cross-check our findings with methane detecting laser systems used in the field,” he said.

“These findings, while not changing the actual emissions, could have significant implications for calculating the emission footprint of the northern cattle industry and also for Australia’s greenhouse gas accounts.”

About half of Australia’s beef herd is located in Northern Australia, defined as Queensland, the Northern Territory, and the northern regions of WA.

Current greenhouse gas accounts indicate that methane from the northern cattle industry contributes about 4.5pc of Australia’s greenhouse gas emissions. The research indicates the actual figure is closer to 3pc.

Dr Charmley said the methods used to determine national greenhouse gas accounts were regularly reviewed, and could soon be adjusted to reflect the results of the CSIRO research.

Another interesting outcome was the role that the tropical forage legume Leucaena can play in reducing cattle emissions.

Cattle in the CSIRO trial that were fed a diet of predominantly Leucaena produced less methane emissions than cattle fed tropical grasses.

“What this nutrition research is showing is that there can be win-win scenarios for the industry and the environment if we can redirect the breakdown of plant material in a way that reduces the amount of methane produced while improving the amount of energy or weight gain that animals get from their feed,” Dr Charmley said.

“We are addressing cattle methane emissions from several angles – from examining the gut microbes that produce methane from ingested pasture and alternative diets, to a landscape focus on northern Australia’s extensive grazing systems using state-of-the-art technologies, such as lasers and wireless sensor networks, to measure and model cattle methane emissions under tropical conditions.”

The Lansdown Research Station near Townsville is one of five national “research hubs” funded by the Australian Government’s Climate Change Research Program, Meat and Livestock Australia and CSIRO.